dantrolene
Brand names: Dantrium
Dantrolene is a muscle relaxant. It helps to reduce muscle spasms and stiffness caused by certain conditions.
Drug Pricing (NADAC)
Generic Price
$0.92/unit
Generic Available
Yes (4 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Dantrolene treats muscle stiffness and spasms from conditions like spinal cord injury, stroke, cerebral palsy, or multiple sclerosis.
Common side effects
Drowsiness, Dizziness, Weakness
Key warnings
Dantrolene can potentially damage your liver.
How It Works
Dantrolene works directly on your muscles to relax them. It reduces the amount of calcium released in muscle cells. This helps to decrease muscle contractions and spasms.
How to Take It
Take dantrolene as directed by your doctor. The usual starting dose for adults is 25 mg once a day. Your doctor may gradually increase the dose every 7 days up to 100 mg four times a day. Take the medicine with water.
Pregnancy & Breastfeeding
Tell your doctor if you are pregnant or plan to become pregnant. It is not known if dantrolene will harm your unborn baby. Talk to your doctor about the risks and benefits of taking dantrolene while breastfeeding.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
Storage
Store dantrolene capsules at room temperature, between 68° to 77°F.
Side Effects (from patient reports)
Based on 411 FDA adverse event reports.
FDA Adverse Event Report Analysis
Detailed analysis of 580 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
580
Death-Related Reports
71
Hospitalization Reports
288
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | DRUG INEFFECTIVE | 94 |
| 2 | NEUROLEPTIC MALIGNANT SYNDROME | 81 |
| 3 | OFF LABEL USE | 53 |
| 4 | PYREXIA | 30 |
| 5 | DRUG INTERACTION | 27 |
| 6 | FALL | 26 |
| 7 | HYPERTHERMIA | 26 |
| 8 | MUSCLE RIGIDITY | 25 |
| 9 | RHABDOMYOLYSIS | 25 |
| 10 | DRUG INEFFECTIVE FOR UNAPPROVED INDICATION | 24 |
| 11 | TACHYCARDIA | 23 |
| 12 | URINARY TRACT INFECTION | 23 |
| 13 | FATIGUE | 22 |
| 14 | HYPERTENSION | 21 |
| 15 | TREMOR | 21 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Dantrolene can potentially damage your liver. Your doctor should monitor your liver function with blood tests. Tell your doctor if you have any signs of liver problems, such as yellowing of the skin or eyes, dark urine, or abdominal pain. If you don't see any benefit after 45 days, stop taking dantrolene.
Known Drug Interactions
Cardiovascular collapse in patients treated simultaneously with verapamil and Dantrolene Sodium is rare. The combination of therapeutic doses of intravenous Dantrolene Sodium and verapamil in halothane/ α -chloralose anesthetized swine has resulted in ventricular fibrillation and cardiovascular collapse in association with marked hyperkalemia.
Mechanism: Combining these drugs may lead to very high potassium levels, which can cause the heart to stop working correctly.
What to do: Use this combination with extreme caution and talk to your doctor about the risks of heart problems.
Concomitant use of carbamazepine with olanzapine, dantrolene, or ibuprofen may increase plasma carbamazepine levels.
Mechanism: Dantrolene can slow down how your body processes carbamazepine, causing the drug to build up in your system.
What to do: Your doctor may need to check your blood levels and watch for side effects.
Common Questions
Can I drive while taking dantrolene?
How long does it take for dantrolene to start working?
Can I take dantrolene with other medications?
What should I do if I experience severe diarrhea?
Is dantrolene a cure for spasticity?
Can I stop taking dantrolene suddenly?
Does dantrolene interact with alcohol?
What if I am over 65?
Can dantrolene cause me to fall?
Will dantrolene help with muscle spasms from arthritis?
What are the common side effects of dantrolene?
Does dantrolene interact with other medications?
What drug class is dantrolene?
Is dantrolene safe during pregnancy?
Related Medications in Direct-Acting Muscle Relaxant
Other drugs grouped near dantrolene — same-class peers and common alternatives.
baclofen
Lioresal, Gablofen
Baclofen is a muscle relaxant.
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botulinum toxin A
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Botox is a drug that blocks nerve signals to muscles.
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carisoprodol
Soma
Carisoprodol is a muscle relaxant.
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chlorzoxazone
Parafon Forte
Chlorzoxazone is a muscle relaxant.
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cyclobenzaprine
Flexeril, Amrix
Cyclobenzaprine is a muscle relaxant.
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What the FDA Data Shows for dantrolene
The FDA label for dantrolene (sold under brand names such as Dantrium) classifies it as a prescription-only medication in the Direct-Acting Muscle Relaxant class. Dantrolene treats muscle stiffness and spasms from conditions like spinal cord injury, stroke, cerebral palsy, or multiple sclerosis. Official labeling lists 6 commonly reported side effects, including Drowsiness, Dizziness, Weakness.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 411 voluntary reports. The database also lists 2 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated minor severity. NADAC pricing from CMS shows a generic unit cost of $0.92.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: December 22, 2024
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages